diff --git a/Packages/MIES/MIES_WaveBuilder.ipf b/Packages/MIES/MIES_WaveBuilder.ipf
index 5737633aba..8f8a50f8ce 100644
--- a/Packages/MIES/MIES_WaveBuilder.ipf
+++ b/Packages/MIES/MIES_WaveBuilder.ipf
@@ -2158,7 +2158,7 @@ End
 Function/S WB_FormulaSwitchToShorthand(variable channelType, string formula)
 
 	variable numSets, i
-	string stimset, shorthand
+	string stimset, shorthand, regex
 
 	if(isEmpty(formula))
 		return ""
@@ -2171,7 +2171,8 @@ Function/S WB_FormulaSwitchToShorthand(variable channelType, string formula)
 		shorthand = epochCombineList[i][%Shorthand]
 		stimset   = epochCombineList[i][%stimset]
 
-		formula = ReplaceString(stimset + "?", formula, shorthand)
+		regex = "(?i)\\b\\Q" + stimset + "\\E\\b\?"
+		formula = ReplaceRegexInString(regex, formula, shorthand)
 	endfor
 
 	return formula
diff --git a/Packages/tests/Basic/UTF_WaveBuilder.ipf b/Packages/tests/Basic/UTF_WaveBuilder.ipf
index c25691db12..ff43b24e3c 100644
--- a/Packages/tests/Basic/UTF_WaveBuilder.ipf
+++ b/Packages/tests/Basic/UTF_WaveBuilder.ipf
@@ -357,3 +357,23 @@ Function WB_StimsetWithNoEpochsAreNotSaved()
 
 	CHECK_EQUAL_STR(ST_GetStimsetList(searchString = basename + "*"), "")
 End
+
+Function CombineStimsetSubStrings()
+
+	string setNameA, setNameAA, setNameCombine
+
+	setNameA  = ST_CreateStimSet("setABC", CHANNEL_TYPE_DAC)
+	setNameAA = ST_CreateStimSet("newsetABC", CHANNEL_TYPE_DAC)
+
+	setNameCombine = ST_CreateStimSet("setCombine", CHANNEL_TYPE_DAC)
+
+	ST_SetStimsetParameter(setNameCombine, "Total number of epochs", var = 1)
+	ST_SetStimsetParameter(setNameCombine, "Type of Epoch 0", var = EPOCH_TYPE_COMBINE)
+
+	ST_SetStimsetParameter(setNameCombine, "Combine epoch formula version", epochIndex = 0, str = WAVEBUILDER_COMBINE_FORMULA_VER)
+	ST_SetStimsetParameter(setNameCombine, "Combine epoch formula", epochIndex = 0, str = LowerStr(setNameA) + "?" + " + " + LowerStr(setNameAA) + "?")
+
+	WAVE/Z wv = WB_CreateAndGetStimSet(setNameCombine)
+	CHECK_WAVE(wv, NUMERIC_WAVE)
+	CHECK_NO_RTE()
+End