diff --git a/src/HeMS.cpp b/src/HeMS.cpp
index a7420e3ab..96e7f0580 100755
--- a/src/HeMS.cpp
+++ b/src/HeMS.cpp
@@ -719,13 +719,13 @@ double HeMS::InterpolateGeEtAlQCrit() {
     double logRadius = log10(m_Radius);
     double qCritLowerMass = (logRadius < lowerLogRadiusLowerMass) ? qLowLow
                           : (logRadius > upperLogRadiusLowerMass) ? qLowUpp
-                          : qLowLow + (upperLogRadiusLowerMass - logRadius) / (upperLogRadiusLowerMass - lowerLogRadiusLowerMass) * (qLowUpp - qLowLow);
+                          : qLowLow + (logRadius - lowerLogRadiusLowerMass) / (upperLogRadiusLowerMass - lowerLogRadiusLowerMass) * (qLowUpp - qLowLow);
     double qCritUpperMass = (logRadius < lowerLogRadiusUpperMass) ? qUppLow
                           : (logRadius > upperLogRadiusUpperMass) ? qUppUpp 
-                          : qUppLow + (upperLogRadiusUpperMass - logRadius) / (upperLogRadiusUpperMass - lowerLogRadiusUpperMass) * (qUppUpp - qUppLow);
+                          : qUppLow + (logRadius - lowerLogRadiusUpperMass) / (upperLogRadiusUpperMass - lowerLogRadiusUpperMass) * (qUppUpp - qUppLow);
 
     double logMass = log10(m_Mass);
     return   (logMass < logLowerMass) ? qCritLowerMass
            : (logMass > logUpperMass) ? qCritUpperMass
-           : qCritLowerMass + (logUpperMass - logMass) / (logUpperMass - logLowerMass) * (qCritUpperMass - qCritLowerMass);
+           : qCritLowerMass + (logMass - logLowerMass) / (logUpperMass - logLowerMass) * (qCritUpperMass - qCritLowerMass);
 }
diff --git a/src/MainSequence.cpp b/src/MainSequence.cpp
index 6315b0ae7..fd04da585 100644
--- a/src/MainSequence.cpp
+++ b/src/MainSequence.cpp
@@ -1305,26 +1305,28 @@ double MainSequence::InterpolateGeEtAlQCrit(const QCRIT_PRESCRIPTION p_qCritPres
         double logRadius = log10(m_Radius);
         double qCritUpperEffLowerMass = (logRadius < lowerLogRadiusLowerMass) ? qUppLowLow
                                       : (logRadius > upperLogRadiusLowerMass) ? qUppLowUpp
-                                      : qUppLowLow + (upperLogRadiusLowerMass - logRadius) / (upperLogRadiusLowerMass - lowerLogRadiusLowerMass) * (qUppLowUpp - qUppLowLow);
+                                      : qUppLowLow + (logRadius - lowerLogRadiusLowerMass) / (upperLogRadiusLowerMass - lowerLogRadiusLowerMass) * (qUppLowUpp - qUppLowLow);
         double qCritUpperEffUpperMass = (logRadius < lowerLogRadiusUpperMass) ? qUppUppLow
                                       : (logRadius > upperLogRadiusUpperMass) ? qUppUppUpp
-                                      : qUppUppLow + (upperLogRadiusUpperMass - logRadius) / (upperLogRadiusUpperMass - lowerLogRadiusUpperMass) * (qUppUppUpp - qUppUppLow);
+                                      : qUppUppLow + (logRadius - lowerLogRadiusUpperMass) / (upperLogRadiusUpperMass - lowerLogRadiusUpperMass) * (qUppUppUpp - qUppUppLow);
         double qCritLowerEffLowerMass = (logRadius < lowerLogRadiusLowerMass) ? qLowLowLow
                                       : (logRadius > upperLogRadiusLowerMass) ? qLowLowUpp
-                                      : qLowLowLow + (upperLogRadiusLowerMass - logRadius) / (upperLogRadiusLowerMass - lowerLogRadiusLowerMass) * (qLowLowUpp - qLowLowLow);
+                                      : qLowLowLow + (logRadius - lowerLogRadiusLowerMass) / (upperLogRadiusLowerMass - lowerLogRadiusLowerMass) * (qLowLowUpp - qLowLowLow);
         double qCritLowerEffUpperMass = (logRadius < lowerLogRadiusUpperMass) ? qLowUppLow
                                       : (logRadius > upperLogRadiusUpperMass) ? qLowUppUpp
-                                      : qLowUppLow + (upperLogRadiusUpperMass - logRadius) / (upperLogRadiusUpperMass - lowerLogRadiusUpperMass) * (qLowUppUpp - qLowUppLow);
+                                      : qLowUppLow + (logRadius - lowerLogRadiusUpperMass) / (upperLogRadiusUpperMass - lowerLogRadiusUpperMass) * (qLowUppUpp - qLowUppLow);
     
         double logMass = log10(m_Mass);
         double interpolatedQCritUpperEff = (logMass < logLowerMass) ? qCritUpperEffLowerMass
                                          : (logMass > logUpperMass) ? qCritUpperEffUpperMass
-                                         : qCritUpperEffLowerMass + (logUpperMass - logMass) / (logUpperMass - logLowerMass) * (qCritUpperEffUpperMass - qCritUpperEffLowerMass);
+                                         : qCritUpperEffLowerMass + (logMass - logLowerMass) / (logUpperMass - logLowerMass) * (qCritUpperEffUpperMass - qCritUpperEffLowerMass);
         double interpolatedQCritLowerEff = (logMass < logLowerMass) ? qCritLowerEffLowerMass
                                          : (logMass > logUpperMass) ? qCritLowerEffUpperMass
-                                         : qCritLowerEffLowerMass + (logUpperMass - logMass) / (logUpperMass - logLowerMass) * (qCritLowerEffUpperMass - qCritLowerEffLowerMass);
-    
-        double interpolatedQCritForZ = p_massTransferEfficiencyBeta * interpolatedQCritUpperEff + (1.0 - p_massTransferEfficiencyBeta) * interpolatedQCritLowerEff;                 // Don't need to use nearest neighbor for this, beta is always between 0 and 1
+                                         : qCritLowerEffLowerMass + (logMass - logLowerMass) / (logUpperMass - logLowerMass) * (qCritLowerEffUpperMass - qCritLowerEffLowerMass);
+
+        double fBeta = (p_massTransferEfficiencyBeta > 0.5) ? (p_massTransferEfficiencyBeta - 0.5) / 0.5 //define a local interpolation factor from 0 to 1 within the selected beta interval
+                     : p_massTransferEfficiencyBeta / 0.5;
+        double interpolatedQCritForZ = fBeta * interpolatedQCritUpperEff + (1.0 - fBeta) * interpolatedQCritLowerEff;     // Don't need to use nearest neighbor for this, beta is always between 0 and 1
         qCritPerMetallicity[ii] = interpolatedQCritForZ;
     }
     double logZlo = -3;                // log10(0.001)
diff --git a/src/changelog.h b/src/changelog.h
index 20cd4638c..f2a2285ff 100644
--- a/src/changelog.h
+++ b/src/changelog.h
@@ -1705,6 +1705,8 @@
 //                                          - Corrected the M&M NS remnant mass prescription to never return a remnant mass larger than the CO core mass (see issue #1468)
 //  03.29.05  AG - May 26, 2026          - Defect repair:
 //                                       - Fix for generalized issue #1378: reinstate "false" fallback option for SN kick angle options (mistakenly changed to "true" in v03.00.00)
+//  03.29.06  DH - September 23, 2026    - Defect repair:
+//                                       - Fix for issue #1484: reversed interpolation factors for mass transfer stability with Ge's model q_crit, in MainSequence and HeMS
 //
 // Version string format is MM.mm.rr, where
 //
@@ -1715,7 +1717,7 @@
 // if MM is incremented, set mm and rr to 00, even if defect repairs and minor enhancements were also made
 // if mm is incremented, set rr to 00, even if defect repairs were also made
 
-const std::string VERSION_STRING = "03.29.05";
+const std::string VERSION_STRING = "03.29.06";
 
 
 # endif // __changelog_h__